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  <title>Document</title>
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<body>
  <script>
    // var climbStairs = function (n) {
    //   let p = 0, q = 0, r = 1;
    //   for (let i = 1; i <= n; ++i) {
    //     p = q;
    //     q = r;
    //     r = p + q;
    //   }
    //   return r;
    // };
    // console.log(climbStairs(5))
    var climbStairs = function (n) {
      if (n == 1) {
        return 1
      }
      if (n == 2) {
        return 2
      }
      return climbStairs(n - 1) + climbStairs(n - 2)
    }
    console.log(climbStairs(5))
  </script>
</body>

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